In his paper "HOW A COCKPIT REMEMBERS ITS SPEEDS",
Edward Hutchins described the concept of distributed cognition using the example of a cockpit. After going through the paper, it becomes evident that although a lot of research can be done on the cognitive capabilities of individuals, it is however impossible to determine the overall 'effective cognition' of a system based purely upon individual studies. This effective cognition is nothing but a conglomeration of the elements and interactions that happen within a system.
Considering the case of a pilot flying an airplane, the overall cognitive capacity of the system directly determines the cognitive capacity of the pilot.
Take for instance the salmon bug. This bug is used by the PNF to determine the deviation in the speed of the aircraft from what it is supposed to be. The width of the speed bug acts as a visual indicator for the deviation and therefore helps the PNF in determining whether an alert must be raised to the PF or not. Had the width been any different, the PNF would have to utilize his/her cognitive resources to calculate the speed difference thereby increasing the overall cognitive load on the system.
Now consider the other speed bugs. Each of these bugs transforms the entire system of the air speed indicator into several spacial divisions. The setting of the speed bugs is equivalent to scribbling on a sheet of paper to make shorthand notes during an interview. These settings are temporal and will only be used during this particular flight landing. The uniqueness of these settings for this particular landing and the duration for which they would be required, make them critical enough to be stored in a long term memory as compared to the other short term auditory messages exchanged between the PNF and the PF.
The transformation of the numerical values into spacial divisions impacts the cognitive representation of the overall system in the mind of the pilot thereby enabling him/her to make decisions much more quickly.
Thus, it can be clearly said that the equipment in the cockpit are not just memory aids. Instead they play a siginificant role in changing the way information is represented in the memory of the pilot, and therefore, directly contribute to the overall cognitive capacity of the cockpit system.